Flexible band reciprocating shaker

ABSTRACT

A reciprocating laboratory shaker ( 10 ) includes a platform ( 12 ) driven by a motor ( 62 ) which is constrained to move in a reciprocating fashion by a pair of flexible bands ( 30, 32 ) located on opposite sides of the platform ( 12 ). A frame ( 24 ), which preferably supports the drive motor ( 62 ), includes a pair of upright supports ( 28 ) which are attached to a pair of wide, but thin, flexible plastic bands ( 30, 32 ) at least at two locations. Each of the two flexible bands ( 30, 32 ) includes a pair of rollers ( 34, 36, 38, 40 ) attached to the inside surface ( 50 ) of the bands ( 30, 32 ). The laboratory platform ( 12 ) is attached to the remaining outside face ( 52 ) of the bands and is driven by the drive motor ( 62 ) having an appropriate crank mechanism ( 54 ). The two flexible bands ( 30, 32 ) constrain the motion of the platform ( 12 ) to substantially a single direction, x, while preventing it from moving in either the y or z directions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a laboratory shaker drive mechanism including apair of flexible bands which restrain the movement of the shakerplatform to a single dimension.

2. Description of Related Art

Laboratory shakers, and the like, are known in the prior art. See, forexample, U.S. Pat. No. 5,593,228 issued on Jan. 14, 1997 and entitled“ROTARY SHAKER WITH FLEXIBLE STRAP SUSPENSION.” The inventor is MyronTannenbaum, Cranbury, N.J., and the patent is assigned to New BrunswickScientific Co., Inc., Edison, N.J., the assignee of the presentapplication. That patent describes a shaker which produces motion in anorbital plane and in which the shaker platform is restrained by twopairs of flexible metal straps.

Another rotary laboratory shaker is described in U.S. Pat. No. 4,183,677issued on Jan. 15, 1980 and entitled “MECHANISM FOR EFFECTING ORBITALMOTION OF A MEMBER”. The inventor is Norman A. De Bruyne, Princeton,N.J. That disclosure also describes the use of flexible members toconstrain the motion of a laboratory shaker platform to an orbitalcircuit.

Devices other than laboratory shakers also include flexible orreciprocating motion drivers. See, for example, U.S. Pat. No. 1,501,625issued on Mar. 10, 1924 to Warren Sadorus and entitled “CORN-POPPINGMACHINE.” That device includes a drive mechanism for constraining themotion of a corn-popping pan to a strictly single dimension.

Also of possible relevance is the disclosure in Russian PatentApplication SU-588-167 entitled “LABORATORY, MULTI-BOWL FEEDER”. Asdescribed in that device a pair of animal feed bowls is driven by asingle shaft through two pairs of flexible straps.

While the prior art appears to describe diverse drive mechanismsincluding flexible drive members, nevertheless, there does not appear tobe any teaching or suggestion of an inexpensive and dependablereciprocating laboratory shaker suitable for use in a laboratoryenvironment.

It was in the context of the above prior art that the present inventionarose.

SUMMARY OF THE INVENTION

Briefly described, the invention comprises a laboratory shaker whichincludes a platform constrained to reciprocate in a single direction bya pair of flexible straps located on opposite sides of the platform. Aframe, including a pair of upright supports, also supports a drivemotor. Each of the upright supports is attached to the outside surfaceof a flexible strap or belt. The pair of flexible belts includes tworollers located at opposite ends thereof which contact the inner surfaceof the flexible belts. The other outer surface, distal from the sideconnected to the frame supports, is connected to the reciprocatingplatform. The laboratory flasks, or other laboratory items, are placedon the platform. The drive motor causes the platform to move only in asingle dimension restricted by the flexible belts.

These and other features of the invention will be more fully understoodby reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of the flexible band reciprocatingshaker platform invention according to the preferred embodiment thereof.

FIG. 2A is a perspective view of the flexible band reciprocating shakerplatform illustrated in FIG. 1 with the chassis and flask support trayremoved.

FIG. 2B is an exploded view of the flexible band reciprocating shakerplatform.

FIG. 3 is a top plan view of the shaker platform with the tray andchassis removed.

FIG. 4 is a side elevational view of the platform mechanism with thetray and chassis removed.

FIG. 5 is a front elevational view of the platform with the tray andchassis removed.

FIG. 6A illustrates the shaker platform in its fully reversed mode.

FIG. 6B illustrates the platform in its central, or neutral, positionbetween the positions illustrated in FIG. 6A and FIG. 6C.

FIG. 6C illustrates the shaker platform in its fully forward mode.

DETAILED DESCRIPTION OF THE INVENTION

During the course of this disclosure, like numbers will be used toidentify like elements according to the different figures whichillustrate the invention.

The preferred embodiment of the invention 10 is illustrated in anassembled perspective view in FIG. 1. Invention 10 includes areciprocating platform 12, that only moves in a forward and backwarddirection, i.e., 1 dimension, not 2 dimensions, which supports a tray 14which in turn supports a plurality of laboratory flasks 16 or Petridishes or the like. A chassis cover 18, or skin, surrounds the internaldrive mechanism and protects it from dust and chemical spills and thelike. Chassis 18 also supports a control panel 20 which may include akey pad 56 for controlling the speed, periodicity, and duration of thereciprocating shaking of the platform 12 and associated tray and flasks16. A control panel 20 could typically include a speed indicator 58 anda time indicator 60. Power is provided to an electric drive motor 62 andthe control panel 20 through a conventional electric cord 22. In manyrespects the outward appearance of the invention 10 is similar to thatof other prior art laboratory devices.

The internal mechanism that drives the platform 12 is best understood byreference to FIGS. 2A to 5, which represent counter-respectivelyorthogonal views of the drive mechanism. Invention 10 is supported by aframe 24 which includes a base 26 and a pair of upright supports 28.Base 26 would also typically support the electric drive motor 62.Electric drive motor 62 is preferably connected to the underside of theplatform 12 through a conventional crank mechanism 54. A number of wellknown crank mechanisms, previously used in the art, would besatisfactory and accordingly, the specific crank mechanism 54,illustrated in the drawings and described herein, is not intended tolimit the universe of crank mechanisms potentially available forinclusion in this invention 10. A crank mechanism 52 would allow foradjustable stroke settings, but is not intended to limit the universe ofcrank mechanisms or other push-pull mechanisms available for inclusionin this invention. Other types of drive mechanisms might includepneumatic drive mechanisms, solenoid drive mechanisms, audio speakerelectromagnetic coil mechanisms, etc.

The pair of upright supports 28 each includes an inward facing surface64. The inward facing surfaces 64 are attached by at least two pair ofattachment means, such as bolts, rivets, metal screws, etc., 42 to theoutside surface 52 of flexible belts 30 and 32, respectively. Theflexible belts 30 and 32 shown in the preferred embodiment of FIGS. 1-6Care two inches wide, 0.0625 inches thick and 22 inches long. Belts 30and 32 are preferably fabricated from polyethylene or could be made fromany other suitable, flexible, but not especially elastic material. Whilebelts 30 and 32 have been described with respect to its preferredembodiment, it will be understood that belts 30 and 32 can be varied inthickness, width and length to accommodate different platform 12 loadsand strokes. In addition, belts 30 and 32 can actually comprise twoflexible discontinuous pieces of material rather than one single strapin view of the fact that the portions of the belts 30 and 32 between theattachment means 42 and 46 do not move. Moreover, it may be desirable toprovide more than two sets of belts 30 and 32, perhaps a pair on bothsides, in order to accommodate heavier platforms and loads. Rollers 34,36, 38, and 40 as shown in FIGS. 1-6C, were made from sections ofstandard PVC pipe, 1 ¼ inch in diameter and 2 inches long.

The first flexible belt 30 includes a pair of rollers 34 and 36 locatedon the inside thereof, and contacting the inside surface 50 of the firstflexible belt 30. Rollers 34 and 36 respectively are attached to thefirst belt 30 by roller/belt attachments 44 which could comprise nails,machine screws, bolts, rivets or the like as shown in FIGS. 2B and 5.Similarly, the second flexible belt 32 includes a pair of rollers 38 and40 located on the inside thereof and contacting the inner surface 50.Rollers 38 and 40 are attached to the second flexible belt 32 by asuitable roller/belt attachment such as wood screws, machine screws,bolts, rivets, etc. 44. Rollers 34, 36, 38, and 40 can be made of anysuitable durable, nonelastic material, such as wood, metal or plastic.

Lastly, the outside surface 52 of each of the flexible belts 30 and 32,opposite the side attached to the upright supports 28, are attached tothe platform 12 by a plurality of suitable support/belt attachments 46which again, might comprise common fasteners such as wood screws,machine screws, bolts, rivets, or the like depending upon the materialsemployed in the platform 12 or the upright supports 28. For example, ifthe upright supports 28 and the platform 12 were made of wood, then woodscrews would be suitable, or if the platform 12 and the upright supports28 were made of thin gauge metal, then sheet metal screws, bolts orrivets might be suitable.

The reciprocating motion of the drive mechanism is illustrated in aprogressive fashion in FIGS. 6A-6C.

In FIG. 6A, the platform 12 is shown in its most withdrawn, i.e.,reversed, position with the platform 12 closest to the rear 68 of themachine and farthest from the front 66 of the machine. In this positionthe rollers 34, 36, 38 and 40 have rotated approximately 60 degrees suchthat the roller/belt fastener 44 are almost adjacent to the downwardfacing portions 70 of the platform 12. The downward facing portions 70of the platform 12 essentially ride on the rollers 34, 36, 38 and 40which in turn ride against the inside surfaces of the two uprightsupports 28.

As the crank mechanism 54 moves forward under the influence of drivemotor 62, the platform is driven towards the central, or neutral,position as illustrated in FIG. 6B. This is the same mode that is alsoseen in FIGS. 3-5. In this case the platform 12 is effectivelyequi-distance between the front 66 and back 68 of the base 26. Moreover,the roller/belt attachments 44 effectively face directly forward andbackward respectively.

Finally, as seen in FIG. 6C, the crank mechanism 54 has advanced to itsother extreme under the influence of drive motor 62 so that the platform12 is closest to the front edge 66 and furthest from the back edge 68.In t his mode the rollers 34, 36, 38 and 40 have rotated approximately60 degrees in the opposite direction from neutral as seen in FIG. 6B, sothat the roller/belt attachment means 44 almost come into contact withthe pair of upward supports 28.

During the t ravel from the extreme positions illustrated in FIGS. 6Aand 6C, the platform 12 smoothly rotates under the influence of rollers34, 36, 38 and 40 and the flexible belts 30 and 32. Because the rollersare effectively in contact with the upright supports 28 and the flatlower portions 70 of the platform 12 all the time, the back and forthride of the platform is very smooth. The flexibility of the belt, givenits minor elastic characteristics, further helps to dampen anyirregularities in the ride.

The invention 10 just described has several advantages over the priorart.

First, be cause the plat form 12 is supported by the belts 30 and 32 andthe rollers 34, 36, 38 and 40 maintain the vertical rigidity of thebelts 30 and 32 throughout the total movement and the fact that therollers 34, 36, 38 and 40 move across flat surfaces separated only bythe thickness of the belts 30 and 32, the motion of the platform 12 issmooth, and not erratic. Additionally, the force required to move theplatform 12 is virtually constant even though relatively increasedplatform 12 loads can be accommodated. Also, the full length of theplatform 12 is maintained a constant horizontal plane throughout thetotal movement.

Second, the mechanism is very sturdy and dependable. This means that ithas a long life, especially under adverse conditions.

Third, the snug fit between the belts 30 and 32 and the surroundingfixed and moving supports 28 and 70, results in a motion devoid ofundesirable or extraneous vertical motion or side play.

Fourth, the mechanism 10 is nearly noise free as compared to likedevices using ball or sleeve bearings. Since many of these shakerdevices are used in a laboratory setting on a continuous basis, a quietrunning machine such as the present invention 10 is very desirable.

Fifth, the concept of the invention is easily adapted for scaling up insize and performance. Larger shakers can be made by increasing the beltthickness a nd width. The stroke length of the larger platform can beincreased by making the roller diameters larger.

Sixth, the materials, fabrication and assembly costs are relativelyinexpensive. The effort and time to repair or maintain the presentinvention 10 is minimal based upon its simplicity. Accordingly, thesystem can be provided to the public at a relatively reasonable andcompetitive cost.

While the invention has been described with reference to the preferredembodiment thereof, it will be appreciated by those of ordinary skill inthe art that modifications can be made to the structure and function ofthe invention 10 with out departing from the spirit and scope thereof.

I claim:
 1. A drive apparatus for a shaker (10) including a drive means(54, 62), said apparatus comprising: a frame (24); flexible band means(30, 32) attached to said frame (24), said flexible band means (30, 32)having an inner surface (50) and an outer surface (52); roller means(34, 36, 38, 40) for contacting said inner surface (50) of said flexibleband means (30, 32); and, platform means (12) attached to said outersurface (52) of said flexible band means (30, 32) and to said drivemeans (54, 62), wherein said flexible band means (30, 32) restricts themotion of said platform means (12) to a substantially reciprocal motion.2. The apparatus of claim 1 wherein said flexible band means (30, 32)comprises at least a first and a second flexible band (30, 32) attachedto opposite sides of said platform means (12).
 3. The apparatus of claim2 wherein said roller means comprises a pair of roller means (34, 36)(38, 40) for contacting said inner surface (50) of said first and secondflexible bands (30, 32), respectively.
 4. The apparatus of claim 3further comprising: first attaching means (44) for attaching said firstand second flexible bands (30, 32) to said pair of roller means (34, 36)(38, 40), respectively; and, second attachment means (42) for attachingsaid first and second flexible bands (30, 32) to said frame (24); and,third attachment means (46) for attaching said first and second flexiblebands (30 32) to said platform means (12).
 5. The apparatus of claim 4wherein said first and second flexible bands (30, 32) comprise aplastic, but substantially non-elastic, material.
 6. The apparatus ofclaim 5 wherein said apparatus comprises a laboratory shaker.
 7. Theapparatus of claim 6 wherein said flexible bands are split in at leastone location.